Nearly 20 per cent of people receiving treatment for hypertension may not actually have a problem, according to a new Canadian study which found that people are often misdiagnosed due to use of manual devices to measure blood pressure.
Researchers at the University of Montreal Hospital Research Centre (CRCHUM) found that more than half of family doctors in Canada are still using manual devices to measure blood pressure, a dated technology that often leads to misdiagnosis.
Automated measurement has the advantage of eliminating what is known as white-coat syndrome, which refers to artificially high blood pressure resulting from the stress of being in a doctor's office and human interaction.
The researchers believe that clinicians should adopt these devices to detect individuals likely to suffer from high blood pressure, researchers said.
Blood pressure is defined as the pressure that the blood exerts on artery walls.
Measured in the arm artery, it is expressed in two numbers: the value when the heart contracts (systolic blood pressure) and the value when the heart relaxes between two contractions (diastolic blood pressure).
Blood pressure is considered normal when systolic pressure is below 140 millimetre of mercury (mmHg) and diastolic pressure is below 90 mmHg. Above these values, a person is said to have high blood pressure (hypertension).
The technology behind tensiometers or sphygmomanometers, the devices used to measure blood pressure, has changed a great deal over the last 20 years, researchers said.
Today, automatic electronic measuring devices, known as oscillometric devices, are available, researchers said.
In 2016, The Canadian Hypertension Education Program (CHEP) Guidelines recommended that electronic measurement is preferable to manual measurement.
An increasing number of medical clinics are equipped with automatic electronic devices.
Janusz Kaczorowski, a medical sociologist from CRCHUM, conducted a survey among Canadian family doctors: 52 per cent of the 769 respondents indicated that they used a manual tensiometer to measure blood pressure. Only 43 per cent used an automatic device.
"Clinicians should use automatic devices," Kaczorowski said.
"They are more expensive but more precise because they take several measurements.

Manual measurement is acceptable if it is properly done, but that is often not the case. To take blood pressure the right way, a 12- to 15-minute period is required. We know that the average visit to a family doctor lasts 10 minutes.
"We have to rethink how patient visits are organised so that the patient can be left alone in a room while the measurement is taken," Kaczorowski said.
The study was published in the journal Canadian Family Physician.

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